unbridle vs bridle

unbridle is not a noun while bridle is a noun.

Word	Noun	Adjective	Verb	Adverb
unbridle	No	No	Yes	No
bridle	Yes	No	Yes	No

unbridle (noun)	bridle (noun)
	the act of restraining power or action or limiting excess
	headgear for a horse; includes a headstall and bit and reins to give the rider or driver control

unbridle (verb)	bridle (verb)
remove the bridle from (a horse or mule)	respond to the reins, as of horses
	put a bridle on
	anger or take offense